1. Field of the Invention
The present invention relates generally to video input devices and more particularly to a remote aiming/input apparatus comprised of a mobile transceiver and a fixed transceiver for use with a raster scanned video terminal and a gaming unit.
2. Description of Related Art
A standard television is an example of a raster scanned video terminal. An image is formed on a video terminal of this type by using a video signal to control an electron beam which scans across the video terminal, line after line, and frame after frame. The electron beam scans from left to right, and from top to bottom. After the electron beam completes a particular horizontal scan line, the electron beam is blanked and then quickly retraced to the left side to begin the next scan line. After an entire frame has been scanned, the electron beam is blanked and then returned to the upper left corner of the video terminal.
In the video signal, the video data for a single frame is preceded by a vertical blanking pulse and, each scan line of the frame is preceded by a horizontal blanking pulse.
There are known video control systems which determine the position of a target area of a television screen that is focused onto a photosensor contained in a user-controlled aiming unit. The known systems typically operate by measuring the time between the beginning of a new frame (i.e. the vertical blanking pulse) and the photosensor's detection of a horizontal scan line (image data) in the target area. Using appropriate software or firmware, it is a relatively simple matter to translate the time measurement into location data. One such system is the GENESIS 16 BIT MEGA SYSTEM.RTM. and an associated LIGHT PHASER.RTM., both manufactured by Sega Corporation.
The Sega LIGHT PHASER transmits video data to the GENESIS 16 BIT MEGA SYSTEM via a cable. Thus, a user is somewhat limited in terms of mobility and must always be conscious of the cable.
Other systems have eliminated the cable hook-up and substituted an infrared IR system wherein the user-controlled aiming unit transmits image data to a separate IR receiver which is hard wired to the main video control unit. However, the known systems are complicated and relatively expensive. Typically, such known IR systems send image data and button press data in data blocks which are asynchronous with the television. Such asynchronous data blocks are typically relatively complicated, requiring header data to identify the beginning of a new data block, and dedicated bit positions with regard to the information being transmitted. An expensive microprocessor is typically required in both the user-controlled aiming unit and in the IR receiver in order to accomplish the necessary encoding and decoding of such data blocks.